Mk1: Trackdays and warped front brake disks - fact of life ?

[Blokey]

.... but all credit to MrT, the Mk2 and Roadster don't seem to suffer from warped disks on track.

You're not trying hard enough! =D>

B.

[BenF]

.... but all credit to MrT, the Mk2 and Roadster don't seem to suffer from warped disks on track.

You're not trying hard enough! =D>

B.

ROFLOL! That's not what you said at the Nurburgring

[BenF]

Anyone tried these disks ?

http://cgi.ebay.co.uk/Cross-Drilled-Mk1 ... dZViewItem

Nope. But I'd steer clear of anything that has been drilled with holes, rather than cast with holes, as drilled holes cause stress in the disks and will crack if pushed hard.

Grooved disks have been OK when I've used them on my Mk1 and Mk2, even for wet trackdays when the cold water -> hot disks causes most problems.

[BenF]

Ben, I can supply you with templates to get an accurate picture of the warp on the disc if you want. See below:

<snip>

Tom

Tom - thanks! I'm tempted to see if I can pick up a dial gauge locally to me this weekend and measure the run-out on the disks that are on the car.

[Icsunonove]

Ben, I can supply you with templates to get an accurate picture of the warp on the disc if you want. See below:

<snip>

Tom

Tom - thanks! I'm tempted to see if I can pick up a dial gauge locally to me this weekend and measure the run-out on the disks that are on the car.

Ben, if I were you I'd just go and get an old one from a tooling place. It'll cost sod all. There's millions of them around 'cos engineering's dieing. Even if it's in thous it doesn't matter.

(P.S I hope no-one thought I just bolted the disc back on after attaching the stepped shim cos I didn't, I'm not that much of a bodge merchant)

[Basirk]

So what did you do? Get a new hub?

[Icsunonove]

Chris, you know this don't you? it was posted on another forum you are a member of. I'll copy it across in case someone else has the same problem, one minute......

Here we go:

Dry fit the brake disc, but don't overtorque the nuts. Just nip it uniformly and check the error has been corrected.

If ok, remove the disc and apply a very thin and uniform smear of copper grease to all the mating surfaces on the disc. Apply a very thin and completely uniform layer of chemical metal to the hub mating face (remember the maximum thickness required should be no more than 0.1mm (or 0.004")).

Fit the disc and gently and diagonally tighten the nuts, checking the runout all the time at the outside edge of the disc. As you tighten the nuts the disc will move. Hopefully if you have applied a really thin and uniform layer of chemical metal the disc should not move much. You should be able to make the very final adjustments to get the discs to run very accurately. Using this method I managed to get both rear discs running to within 0.02mm or 0.001", measured at the very outside edge of the disc. The maximum acceptable runout according to the Haynes manual is 0.15mm or 0.006", so I am well satisfied with the job.

If anyone needs to do this procedure I will provide further details and will supply all the templates shown above.

Hope this helps someone else, Tom

[Blokey]

.... but all credit to MrT, the Mk2 and Roadster don't seem to suffer from warped disks on track.

You're not trying hard enough! =D>

B.

ROFLOL! That's not what you said at the Nurburgring

...I could repeat it but the Sweary Mary Police might come and get me

...although your language was a little colourful on that occasion too IIRC. Let's turn in to this corner...err...no - it's ok - have another go......errr....ok - no worries - make it the best of three [-o< ...wasn't worried at all

Come along and have some more goes in mid September

B.

[BenF]

You're not trying hard enough! =D>

B.

ROFLOL! That's not what you said at the Nurburgring

...I could repeat it but the Sweary Mary Police might come and get me

...although your language was a little colourful on that occasion too IIRC. Let's turn in to this corner...err...no - it's ok - have another go......errr....ok - no worries - make it the best of three [-o< ...wasn't worried at all

Come along and have some more goes in mid September

B.

Well, I was just getting value for money from the corner ... possibly been slightly distracted and off-line by overtaking something just before that.

I can remember some 'rearrangement' of your seating position after we'd get around that corner finally ..

[Blokey]

Many things were rearranged after that corner! LOL. Well driven though =D>

I'm going to be fitting new pads and disks all round along with new fluid and if I can something that'll keep the exhaust attached (also may invest in some Fensport engine mounts) slightly more permanently than it is at the moment.

I'll give the ideas in here a go and report back....

B.